(display "\n========================================\n")
; 方式一：
(define (make-segment start end)
    (list start end))

(define (start-segment segment)
    (car segment))

(define (end-segment segment)
    (cadr segment))


; 方式二
(define (make-segment start end)
    (cons start end))

(define (start-segment segment)
    (car segment))

(define (end-segment segment)
    (cdr segment))

(display "\n========================================\n")